Long projections from the brainstem to the lumbar cord activate locomotion. Using in vitro neonatal rats our laboratory showed that relay (propriospinal - PS) neurons also contribute to transmission of the locomotor signal. This thesis examines whether locomotor-related PS neurons exist in adult mammals, which has important clinical implications. The brainstem of adult decerebrate rats was stimulated to elicit stepping. The following manipulations were performed: 1) suppression of synaptic transmission to PS neurons, 2) lesioning of direct bulbospinal projections to lumbar segments, and 3) neurochemical excitation of PS neurons. In addition, in the absence of brainstem stimulation, the ability of neurochemically excited PS neurons to induce stepping was examined. Brainstem-evoked locomotion was suppressed by synaptic blockade, enhanced by PS neuron excitation, persists after lesioning of long-direct projections, and hindlimb stepping was elicited by PS neuron excitation alone. The findings support the existence of a locomotor-related PS system in adult mammals. / October 2016

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Undergraduate honors paper--Mount Holyoke College, 2006. Dept. of Biological Sciences. / Includes bibliographical references (leaves 53-56).

No description available.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

No description available.

No description available.

Snakes are one of the world’s most versatile organisms, at ease slithering through rubble or climbing vertical tree trunks. Their adaptations for conquering complex terrain thus serve naturally as inspirations for search and rescue robotics. In a combined experimental and theoretical investigation, we elucidate the propulsion mechanisms of snakes on both hard and granular substrates. The focus of this study is on physics of snake interactions with its environment. Snakes use one of several modes of locomotion, such as slithering on flat surfaces, sidewinding on sand, or accordion-like concertina and worm-like rectilinear motion to traverse crevices. We present a series of experiments and supporting mathematical models demonstrating how snakes optimize their speed and efficiency by adjusting their frictional properties as a function of position and time. Particular attention is paid to a novel paradigm in locomotion, a snake’s active control of its scales, which enables it to modify its frictional interactions with the ground. We use this discovery to build bio-inspired limbless robots that have improved sensitivity to the current state of the art: Scalybot has individually controlled sets of belly scales enabling it to climb slopes of 55 degrees. These findings will result in developing new functional materials and control algorithms that will guide roboticists as they endeavor towards building more effective all-terrain search and rescue robots.

Thesis (M.S.)--Ohio University, June, 2001. / Title from PDF t.p.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 54-56). Also available on the World Wide Web.